Water-soluble polymers of nu, nu&#39;-ethylene-bis-acrylamide



WATER-SOLUBLE POLYMERS OF N,N'-ETHYL- ENE-BIS-ACRYLAMIDE 5 Lennart Albert Lundberg, Stamford, C'onn., assignor to American Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Application November 21, 1956 Serial No. 623,555

16 Claims. or. 260-883) This invention relates to a method of making high molecular weight polymers and to the product produced thereby. More particularly, the present invention relates to high molecular weight water-soluble, cationic polymers which are obtained by reacting an alkylidene acrylamido compound (I) containing at least two acrylamido, i.e. 20

groups, wherein R is selected from the group consisting of hydrogen, and alower alkyl radical with a nitrogen compound (II) containing at least three hydrogen atoms linked to the nitrogen atoms thereof. Polymers of the present invention are obtained asga result of addition of the primary amine groups to the unsaturated groups of the acrylamido compound and, the resulting addition product reacts further through the sec-ff; ondary amine groups with residual unsaturated groups resulting in branching and eventually cross-linking of chains, unless the reaction is terminated, to give water- 3 insoluble resins.

According to the present invention, I have found that a high molecular weight stable water-soluble polymer may be obtained by reacting compounds of this type. Two techniques may be employed to obtain the water- 40 soluble polymer of the invention. The water-soluble stable polymer may be obtained by reacting the compounds of the type of (I) and (II) in nearly equimolar quantities until the reaction proceeds to a point just short of the gel stage and stabilizing the polymer by the ad- 5 dition of a secondary amine to terminate the reaction. By this technique I have found that the secondary amine which is added just before irreversible gelation occurs, reacts preferentially with the residual vinyl groupings remaining in the mixture and inhibits cross-linking of the reaction product to the water-insoluble stage.

As an alternate procedure, a stable water-soluble material may be obtained by using a low enough ratio of the alkylidene acrylamido compound (I) to the nitrogen compound (II) so that although the reaction proceeds to completion the polymer remains soluble. In following this latter procedure, some sacrifice may result in molecular weight and degree of branching due to deficiency of one of the reacting groups responsible for chain growth.

- The products obtained in the present invention have 0 no residual vinyl groups in the polymer, i.e. there is no carbon to carbon unsaturation in the polymers produced.

It is an object of the present invention to prepare high molecular weight water-soluble cationic polymers of an (I) acrylamido compound and (II) a nitrogen-containing 5 compound wherein at least three hydrogen atoms are linked to the nitrogen atoms.

It is a further object of the present invention to pro vide a novel process for making stable high molecular weight water-soluble polymers by reacting compounds of 7 the type (I) and (II) as hereinafter more fully described.

According to the invention, the high molecular weight water-soluble polymers contemplated are those obtained by reacting in an aqueous medium (I) a compound of the group (a) having the formula and (b) having the formula wherein R'-CH is the hydrocarbon residue of an aldeformula 1 wherein Rf is asubstituent selected from the group consisting of hydrogen, an alkyl radical and an aryl radical, x is an integer of at least 2, and fy is an integer having a value of from 08; aromatic diamines; and ammonia. v

Suitable diacrylamido compounds within the scope of the invention, i.e. those having the formula NHCOC=CH1 Nnooc=om wherein R-CH and R are substituents as above defined, are known and may be prepared for example in the manner described in the L. A. Lundberg U.S. Patent 2,475,846.

In the compounds of this formula, the R -.-CH .group may be derived as the hydrocarbon residue of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, pentanal, capryl aldehyde, lauric aldehyde, crotonaldehyde, benzaldehyde, furfural, salicylaldehyde, cinnamic aldehyde, or the like. In other words, R may be hydrogen, alkyl, alkenyl, aralkyl, aralkenyl, aryl or heterocyclic. Instead of formaldehyde itself, para-formaldehyde or a substance yielding formaldehyde such as hexamethylene-tetramine may be used to produce the'alkylidene-bis-acrylamide resin intermediates.

The compounds of this type having the two acrylamido groups are such as for example N,N-methylene-bis-acrylamide and N,N'-methylene-bis-methacrylamide.

The cyclic compounds containing three acrylamido 0r groups, i. e. compounds of the type as hexahydro-l,3,5-

- 4 reaction vessel and reacted. The reaction is continued until a point just short of the gel stage at which time the polymerization reaction product is stabilized by the addition of a secondary amine to the reaction mixture. The

secondary amine terminates cross-linking of the polymer triacryl-s-triazines, may be prepared as described in the by reacting preferentially with the residual unreacted Zerner et al. US. Patent 2,559,835. vinyl groups in the mixture. The results obtained by re- The nitrogen-containing compound (II) containing at acting various combinations of compounds of the type least three hydrogen atoms linked to the nitrogen atoms (I) and (II) in nearly equimolar amounts, the reacting are such as ammonia; various polyalkylene polyamines conditions, and the resultsobtained including comparaincluding ethylene diamine, diethylene triamine, tricthyltive examples are set forth in the following tables. ene tetramine, tetraethylenepentamine, pentamethylene Table II shows the results obtained with further exhexamine, trimethylene diamine, ethylenebisoxypropylamples using N,N-methylene-bis-acrylamide as compound amine, iminobispropylamine, methyliminobispropylamine (I) and various other nitrogen-containing compounds, inand the like; and including N aryl substituted alkylene cluding ammonia as compound (II) and as the chain terpolyamines such as N-phenylethylenediamine and N- minating secondary amine, dimethylamine.

TABLE I N,N-Meth- Example ylenebis- Nitrogen Compound and Water Maximum Time Secondary Remarks Acrylamide Parts Temperature (Minutes) Amine (Parts) 1 30.8 1,3-diamino butane, 17.6-.. 77.6 Stgggngbath, 17 None Gelled. 2 (Comparative)... 30.8 do 73 65 C: 13 Diethylamine, Clear water-white syr- 7.3. upy solution stable on heating with v. (NI 14)2S202. 3 30.8 Ethylene diamine (69% 63.8 70C 6 Diethylamine, Soiut1onviscous wateraqueous solution), 17.4. 3.7. white. 4 (Comparative)... 30.8 Ethylene diamine (69%), 68.8 70 C About 3 min Diethylamine, Solutionthin, watery. 17.4. 7.3. Stable 1ufpon heating with (N 01320:. 5 31.9 Triethylenetetramine, 61.4 C.=i:1-.... 7 do Viscous solution. Stable 29.6. upon heating with (NHDzSrOa. 6 (Comparative).-. 31.9 .-..-do 61.4 C.:l:1-...- 8 None Gel within 10 minutes after cooling to room temperature.

TABLE II N,N-Meth- Time Example ylenebls- Amine and Parts Water Temperature Before Dimethyl- Time Remarks Acrylamide Stopping amine (Parts) (Minutes) 7 31.8 Trimethylenedi- 63.8 25 C. rose to 5 4.5 Slightly cloudy viscous amine, 14.8. 59" C. 0.1 mole solution. ComparatlveExample 31.8. do 63.8 6.5 Gelled.

31.8 Ethylenebisoxy- 63.8 25 C., rose to l3 4.8 Viscous solution.

ggrgpylamine, 52 0. Comparative Example-.... 31.8 ..& 5 63.8 .-do..-. 15 Viscous solution gelled when on steam bath 3% minutes. 9 31.8 Iminobispropyl- 63.8 25 C.,rose to. 2 4.8 Viscous solution.

amine, 26.2. 68 C. 1 Comparative Example 31.8 do 63.8 do 3 Gelle'd. 10 31.8 Methyliminobis- 63.8 25 C., rose to 9%. 4.8 'Viscous solution.

gopylamine, 54 C. I .0. Comparative Example....- 31.8 do 63.8 7 12% Very viscous-gelled when on steam bath 3% minutes.

phenylpropylenediamine. Aromatic diamines such as Example 11 those havmg the formula NH Following the procedured described above, 49.8 parts of hexahydro-l,3,5-triacryl-s-triazine and 29.6 parts of R triethylene tetramine are added to 79.4 parts of water 50 and held at a temperature of 50 C.:2 C. for 5 min- NHi utes. The reaction. product becomes very viscous. At wherein 3 is an alkyl containing 0 to 1 carbon, atoms thlS. stage, 7.3v parts of drethylamine are immediately h as h 1 dja i d -di i phenyl added and the m xture 18 heated over steam bath for 30 pane fo example may also b used i whole or in part minutes. A viscous resinous solution which may readily as the nitrogen-containing component (11.) of the. reaction f l be dissolved in water isobtai i mixture. p E I H The invention will be described in greater detail. in connection with the. following specific examples in which. [p-CPhenylene dlamine-NHw-CoHr-NH:.] the proportions given are parts by Weight unless other- 1 wise expressly stated. Parts Moles In making the water-solublepolymer using the second- 1 1 ary amlne to stabilize the resin, the chosen quantities (1) p-pheuylene diamiue. 21.62 02 of the acrylamido-containing compounds (I) and the lflnfthylene'bisacrylamde gggg 0 2 nitrog n-containing compounds (II) are dissolved in (4) acetic acid, glacial 12.0 0 2 water at approximately room temperature in a. suitable The above ingredients are charged into the reaction vessel and heated by means of a steam bath. The solid reactant dissolves upon heating to 88 C., giving a lavendish black colored solution. The reaction product gels to a water-insoluble condition upon heating two hours.

The above reaction is repeated. After heating 1.5 hours at a temperature of 8890 C., 5.84 parts (0.08 mole) of diethylamine is added. The viscous resinous syrup is heated 1% hours longer without any noticeable change in viscosity. The viscous nearly black resinous syrup iscompletely miscible with water.

Illustrative of the secondary amines which may be employed to terminate the reaction between compounds of the type of (I) and (II) before the copolymerization of these compounds has advanced to the water-insoluble gel stage are such as dimethylamine, diethylamine, diethanolamine, N-methylethanolamine, cyclohexylmethylamine and aromatic secondary amines such as monomethyl aniline.

The proportions of the acrylamido compound (I) to the nitrogen-containing compound (II) may be varied. Generally the molar ratio of (I) to (II) is maintained within the rage of 0.421 to 3:1 respectively. It will be understood that when the acrylamido compound of type (I) is a cyclic trisacrylamido compound rather than the bisacrylamido compounds, the mole proportion of this compound to the amino-type compound (II) may be correspondingly diminished. Thus, when the bisacrylamido compounds are utilized, I have found that a mole ratio of (I) to (II) of about 0.6:1 to 3:1 may be employed, preferably 0.8:1 to 3:1, and when employing the trisacrylamido compounds a ratio of (I) to (II) in the range of 0.4:1 to 3:1 preferably 0.6:1 to 3:1 is employed. When it is desired to conduct the reaction so as to avoid using a secondary amine and yet obtain a stable water-soluble product the mole ratio of compounds (I) to (II) should be less than about 0.85 in the case of the bisacrylamido compound and less than about 0.65 mole in the case of the trisacrylamido compound. "In using these ratios the reactants may be carried to completion without cross-linking of the composition to a waterinsoluble state occurring, as the mole ratios of acrylamido compound to polyamine when reacted to substantial come molar amount of alkylidene acrylamido compound to polyamine and 0.80 is sufiicient. For example where 1 mole alkylidene-bis-acrylamide per mole polyamine is reacted, the'amount of secondary amine would be (1 less 0.8) times 2.5 or 0.5 mole of secondary amine. None of the products stabilized with diethylamine gelled upon heating with a catalytic amount of (NHQ S O indicating no residual vinyl groupings are present.

The temperature at which the reaction is carried out may be varied considerably, although it is preferably conducted at a temperature of from about C. to about 90 C. At lower temperatures, polymerization proceeds slowly whereas high temperatures may be disadvantageous in that the polymerization may advance so rapidly at the point close to the gel stage as to prevent the timely addition of the secondary amine prior to the time the water-insoluble condition of the resin is reached.

The following examples, set forth in Tables IH and IV, further illustrate the nature of the reaction and provide a suitable technique in determining the stage, prior to gelation, at which the secondary amine is added to produce a high molecular weight water-soluble product. Table III shows the results of varying the mole ratios of compounds (I) to (II). In the lower ratio of acrylamido compound, i.e. N,N'-methylene-bis-acrylamide (MBA) to nitrogen compound, i.e tetraethylene tetramine (TETA) Examples 13-15, the reaction is carried to completion and the product remains water-soluble whereas in Example 16, the reaction proceeds to a waterinsoluble stage unless the reaction is terminated short of the gel stage by the addition of a secondary amine, as in Example 17. V I The procedure employed for Examples 13-17 is as follows: The TETA is added rapidly to a slurry of MBA in water. solids.) The temperature rises rapidly to a maximum temperature of -75 C. In the preparation of Example 17, the reaction is allowed to continue until a noticeable viscosity change begins to take place; Soon after this stage (1-2 minutes) is reached, the diethylamine is added at a time as determined and described below. After 15 minutes, the resulting clear syrup is heated at a temperature of 90 C.-92 C. over a steam bath for 30 minutes.

TABLE III MBA TETA Viscosity- Example Gardner-Holdt Parts Chain Bubble Vis. H20 Terminator moles parts moles parts Tubes 13 0.6 37. 0 1 58. 4 I (2.25 poise) 95. 4 None. 1 0.7 43.2 1 58. 4 N (3.4 poise) 101. 6 None. 15 0.8 49. 3 l 58. 4 W (10.7 poise)--- 107. 7 None. 16 0. 9 65. 4 1 58. 4 X (12.9 poise)..-.- 113. 8 None. 17' 0. 9 55. 4 1 58. 4 X (12.9 p0ise) 113. 8 14.6 parts d1- eltlgylamine I Gelled Within 12 minutes. I b Diethylamine added 9 minutes from start of reaction.

pletion are below the stage at which cross-linking takes lace. p When a secondary amine is used to stabilize the copolymer' in a water-soluble condition before the reaction has advanced to the water-insoluble gel stage, an amount at least suflicient to terminate further interreaction between the components (I) and (II) of the mixture should be employed. Althoughthe amount of secondary amine used for this purpose is not critical, generally an amount to a slurry of MBA and water while holding the temperature between 25 and 30 C. by external-cooling. The

equivalent to 2.5 to- 3 times the difference between the addition required from 2-3 minutes.

TABLE IV PREPARATIONS INVOLVING USE OF CHAIN TERMINATOR MBA TETA Chain Termi- Reaction Time No Chain H O, nator (DEA) Percent Before Adding Terminator Viscosity of Example. Part Solids DEA, Min. Added, Stabilized at 25-30 C; Time Product Mole Part Mole Part Mole I Part to gel 18 1 v 154. 1 Q 1 146 4.62.5 0. 6 43. 8 41.3 40 I 50 K,(2.75 poise); 19 1. 5 231 1 146 554. 5 2. 1 153. 5 44. 1 39 g 4344 U-Vi (6).28.8

- p se 20; 2.0 308.2 1 146 680.5 3.6 262.8 46.1 45 59 B0 (0).'65.0.85

' poise 21- 2.0 308.2 1- 146 680.5 3.6 262.8 46.1 55 58. J (2.5 poise).

In order that the reaction does not progress too rapidly to aflord opportunity for timely stopping the polymerization, the temperature is preferably not allowed to climb above 30 C. After 25-30 minutes, practically all of the solid has dissolved. A sample is taken up in a 25 ml. volumetric pipette, and the time to drain is measured using a stop watch (the pipette employed had the same size opening at the. bottom as at the top to afford uniform flow). A check on the viscosity is made in this manner every 4-5 minutes. When the time for a sample to flow through the pipette increases from -7 seconds to about 30-35 seconds, the diethylamine is quickly added. A sample is removed prior to adding diethylamine and the time to gel noted (measured from the time the diethylamine is added to bulk of resin syrup).

Data recorded for Example 21 showing the increase in viscosity as determined by flow of samples through the pipette follows:

Samples Drawn, Time Time to Flow Through Pipette The water-soluble cationic polymers. of this invention have certain advantage over those obtained by reacting a polyalkylene polyamine with an alkylene halide for some applications in that no mineral acid such as hydrochloric acid is liberated. The resulting products are obtained as the free base which is desirable particularly Where the products are'tobe used. as modifiers for cellulosic materials such as paper, textiles and the like.

Various modifications Within the contemplation of the I invention will be apparent to those skilled in the art, and

the invention is not intended to be limited to the specific details enumerated except as expressed in the appended claims.

I claim:

1. A process of preparing a high molecular weight water-soluble copolymer comprising reacting in an aqueous medium a compound ,(I) selected from the group (a) having the formula.

and (b) having the formula wherein R" is a substituent selected from the group consisting of hydrogen, an alkyl radical and an aryl radical, x is an integer of at least 2, and y is an integer having a value from 0-8, aromatic diamines and ammonia, in a mole ratio of (I) to (II) of 0.6:1 to 3:1, respectfully, at atmospheric pressure and at a temperature of from about 20 C. to about C. to a point short of the gel stage and terminating further polymerization by the addition of sutficient amount of a mono secondary amine to react with the residual vinyl groups of said copolymer.

. 2...A process of preparing a high molecular weight water-soluble copolymer comprising reacting in an aqueousmedium (I) N,N-methylene-bis-acrylamide and a compound (II) selected from the group of low molecular weight alkylene polyamines having the general formula l i" n mom) Mon) NE:

wherein R is a suhstituent selected from the group consisting of hydrogen, an alkyl radical and an aryl radical, 'x is an integer of at least 2,, and y is an integer having a value from O-8, aromatic diamines, and ammonia, in a mole ratio of-(I.) to (II) of 0.8:1 to 3:1 respectively, at atmospheric pressure and at a tempera ture of from about 20 C. to. about 90 C. to a point short of the gel stage andv terminating further polymerization by the addition of sufficient amount of a mono secondary amine to react withvthe residual vinyl groups of said copolymer.

3. A process. of preparing, a. high molecularweight lg, Water-Soluble copolymer comprising reacting in an aqueous medium (I) hexahydro-l,3,S-triacrylyl-s-triazine and a compound (II) selected from the group of low molecular weight alkylene polyamines having the general wherein R" is a substituent selected from the group consisting of hydrogen, an alkyl radical and an aryl radical, x is an integer of at least 2, and y is an integer having a value from -8, aromatic diamines and ammonia, in a mole ratio of (I) to (II) of 0.6:1 to 3:1, respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and terminating further polymerization by the addition of sufiicient amount of a mono secondary amine to react with the residual vinyl groups of said copolymer.

4. A process of preparing a high molecular weight water-soluble copolymer comprising reacting N,N'- rnethylene-bis-acrylamide and ethylenediamine in a mole ratio of 0.8:1 to 3:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage. and terminating crosslinking in the reacting mixture by the addition of a mono secondary amine equivalent in amount to about 2.5 to 3 times the ditference between the amount of said methylene-bis-acrylamide and said ethylenediamine and 0.8.

5. A process of preparing a high molecular weight water-soluble copolymer comprising reacting N,N'- methylene-bis-acrylamide and triethylenetetramine in a mole ratio of 0.8:1 to 3:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and terminating cross-linking in the reacting mixture by the addition of a mono secondary amine equivalent in amount to about 2.5 to 3 times the difference between the amount of said methylene-bis acrylamide and said triethylenetetraamine and 0.8.

6. A process of preparing a high molecular weight water-soluble copolymer comprising reacting N,N'- methylene-bis-acrylamide and bisiminopropylamine in a moleratio of 0.8:1 to 3:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and terminating cross-linking in the reacting mixture by the addition of a mono secondary amine equivalent in amount to about 2.5 to 3 times the difference between the amount of said methylene-bis-acrylamide and said bisiminopropylamine and 0.8.

7. A process of preparing a high molecular weight Water-soluble copolymer comprising reacting N,N'- methylene-bis-acrylamide and ammonia in a mole ratio of 0.8:1 to 3:1 respectively -at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and terminating crosslinking in the reacting mixture by the addition of a mono secondary amine equivalent in amount to about 2.5 to 3 times the difference between the amount of said methylene-bis-acrylamide and said ammonia and 0.8.

8. A process of preparing a high molecular weight water-soluble copolymer comprising reacting hexahydro- 1,3,S-triacrylyl-s-triazine and triethylenetetramine in a mole ratio of 0.6:1 to 2:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and terminating cross-linking in the reacting mixture by the addition of a mono secondary amine equivalent in amount to about 2.5 to 3 times the difference between the amount of said hexahydro-1,3,S-triacrylyl-s-triazine and said triethyl enetetramine and 0.8. p

9. A composition of matter comprising a high molecular weight water-soluble addition reaction product, free 10 of vinyl groupingsobtained by reacting a compound (I) selected from the group (a) having the 'formula NHc0o=oH| NHC0C=CH1 and (b) having the formula wherein R-CH is the hydrocarbon residue of an aldehyde and R is a member of the group consisting of hydrogen and alkyl radicals having 1 to 4 carbon atoms, and a compound (II) selected, from the group of low molecular weight alkylene polyamine of the general formula i wherein R" is a substituent selected from the group consisting ofhydrogen, an alkyl radical and an aryl radical, x is an integer of at least 2, and y is an integer having a value from 0-8, aromatic diamines and ammonia, in a mole ratio of (I) to (II) of 0.4:1 to 3:1, respectively, at atmospheric pressure and at a temperature of from about 20 C. to about C. to a point short of the gel stage and admixing therewith a mono secondary amine.

10. A composition of matter comprising a high molecular weight water-soluble polymerization reaction product obtained by reacting a compound (I) selected from the group (a) having the formula "x"- is an integer of at least 2, and y is an integer havinga valuefrom -8 and ammonia in a mole ratio of (I) to (II) of 0.6:1 to 3:1, respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and admixing therewith a mono secondary amine.

11. A composition of matter comprising a high molecular weight water-soluble copolymerization reaction product obtained by reacting (I) N,N'-methylene-bisacrylamide and a compound (II) selected from the'group of low molecular weight alkylene polyamine of the general formula wherein R" is a substituent selected from the group consisting of hydrogen, an alkyl radical and an aryl radical, x is an integer of at least 2, and y is an integer having a value from 0-8, an aromatic diamine and ammonia in a mole ratio of (I) to (II) of 0.8:1 to '321 respectively, at atmospheric pressure and ata tempera: ture of from about 20 C. to about 90 C. to a point short of the gel stage and admixing therewith a mono secondary amine.

12. A composition of matter comprising ahigh molecular weight'water-soluble reaction product obtained by reacting N,N'-methylene-bis-acrylamide and ethylenediamine in a mole ratio of 0.8:1 to 3:1 respectively, at atmospheric pressure and a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and admixing therewith a mono secondary amine.

' 13. A composition of matter comprising a high molecular weight water-soluble reaction product obtained by reacting N,N'-methylene-bis-acrylamide and triethylenetetramine in a mole ratio of 0.811 to 3:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about C. to a point short of the gel stage and admixing therewith a mono secondary amine.

14. A composition of matter comprising a high molecular weight water-soluble reaction product obtained by reacting N,N-methylene-bis-acrylamide. and bisiminopropylamine in a mole ratio of 0.8:1 to 3:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and admixing therewith a mono secondary amine.

15. A composition of matter comprising a high molecular weight water-soluble reaction product obtained by reacting N,N'-methylene-bis-acrylamide and ammonia in a mole ratio of 0.8:1 to 3:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and admixing therewith a mono secondary amine.

16. A composition of matter comprising a high molecular weight water-soluble reaction product obtained by reacting hexahydro-l,3,5-acryly1-s-triazine and triethylenetetramine in a mole ratio of 0.6:1 to 3:1 respectively, at atmospheric pressure and at a temperature of from about 20 C. to about 90 C. to a point short of the gel stage and admixing therewith a mono secondary amine.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS OF PREPARING A HIGH MOLECULAR WEIGHT WATER-SOLUBLE COPOLYMER COMPRISING REACTING IN AN AQUEOUS MEDIUM A COMPOUND (I) SELECTED FROM THE GROUP (A) HAVING THE FORMULA 